AT521582A1 - Plastic molding machine and method for checking such - Google Patents

Abstract

Plastic molding machine with at least one component which is exposed to a force and / or a counterforce counter to the force by at least one drive, characterized in that at least one ultrasound device (10) with at least one transmitter unit (10.2) for transmitting and at least one receiver unit (10.1) For receiving ultrasound, the ultrasound device (10) is connected or can be connected to an evaluation unit (7), the at least one transmission unit (10.2) being arranged on the at least one component and / or being connected to the at least one component via a sound-conducting connection and / or is integrated in the at least one component and the at least one receiving unit (10.1) is arranged on the at least one component and / or is connected to the at least one component via a sound-conducting connection and / or is integrated in the at least one component and the evaluations are Unit (7) is designed to determine a change in dimension and / or a change in position of the at least one component directly or indirectly on the basis of a measurement of the at least one ultrasound device (10) and to output a message based on the measurement which is relevant to the force itself and / or an effect of the force on the plastic molding machine and / or a molding tool (13) is representative.

Description

The present invention relates to a plastic molding machine with the

Features of the preamble of claim 1 and a method for checking at least one component of a plastic molding machine.

Plastic molding machines can be understood to mean plastic processing machines, such as injection molding machines, injection presses and the like. The state of the art is described below using injection molding machines as an example. However, analogous statements apply generally to plastic molding machines.

Closing units for injection molding machines familiar in the prior art have at least two mold mounting plates which are suitable for transmitting a clamping force to a mold tool mounted thereon. This clamping force is required to keep a mold closed under injection pressure (and the resulting internal mold pressure).

Molds have two or more mold parts which form a cavity in the closed state. This cavity has the geometric dimension of a component to be molded. When the mold is closed, molding compound is introduced into the cavity of the mold. The molding tool is kept closed until the molding compound has substantially hardened. In order to eject the molded part to be produced from the mold, the mold is opened and the molded part produced is ejected, for example, by means of an ejector unit.

In many cases it is desirable to measure the actual closing force, for example for monitoring purposes, independently of the closing force mechanism. Closing forces that are both too low and too high can lead to damage to the molding tool.

It is therefore known from the prior art to equip generic clamping units for plastic molding machines with measuring sensors, so that clamping force sizes can be determined and / or positions of the mold clamping plates, / 46

83163 28 which provide information on the gaping of the mold. Strain gauges (strain gauges) can be used as measuring sensors

DMS can be traced back to a position or a force. Such strain gauges are applied to components of the clamping unit and the mold in order to measure the deformation of these components.

The provision of such measuring devices is usually associated with high expenditure in terms of production technology, since it is often not a trivial solution to arrange such measuring devices at the measuring points. Strain gauges must always be arranged in a force flow in order to receive representative measurement signals, which means that they are always exposed to the risk of damage due to the application of force. Another disadvantage of using strain gauges is that the dimensional accuracy is not very high.

Furthermore, it is desirable to be able to determine injection forces that occur when injecting in an injection molding machine. For the injection of the plastic in an injection molding machine, the plasticizing screw (which is also used for plasticizing the molding compound) is moved in the axial direction in the plasticizing cylinder by, for example, a spindle and a drive unit connected to it, in order to introduce the plasticized molding compound from the plasticizing cylinder into the cavity of the mold . In order to determine an injection force or an injection pressure, it is common to measure the load applied to the drive unit and to use this load to conclude that there is a resistance (injection force or pressure). However, such a procedure provides values for the actually prevailing pressures and forces only to a limited extent, since, due to the prevailing friction and pressure conditions, only relatively poor accuracy and resolution can be achieved. Taking into account the friction in particular places limits on the accuracy.

The same applies to an ejector unit of a plastic injection molding machine. The ejector unit can also be moved in the linear direction by means of a spindle and an associated drive unit. Here, too, the desire arises from the state of the art for a measurement method for the more reliable and precise measurement of occurring forces.

/ 46

83 163 28

The object of the invention is therefore a plastic molding machine and a

To provide a method by which the plastic molding machine during the

Operation and with the least possible impairment of the manufacturing process becomes more accessible.

With regard to the plastic molding machine, this object is achieved by the features of claim 1. This is done by providing at least one ultrasound device with at least one transmitting unit for transmitting and at least one receiving unit for receiving ultrasound, which ultrasound device is or can be connected to an evaluation unit, wherein

- The at least one transmitter unit is arranged on at least one component and / or is connected to the at least one component via a sound-conducting connection and / or is integrated in the at least one component and

- The at least one receiving unit is arranged on the at least one component and / or is connected to the at least one component with a sound-conducting connection and / or is integrated in the at least one component and

- The evaluation unit is designed to determine a change in dimension and / or a change in position of the at least one component directly or indirectly on the basis of a measurement of the at least one ultrasound device and to output a message based on the measurement, which is for the force itself and / or an effect the force on the plastic molding machine and / or a mold is representative.

With regard to the method, the object is achieved by the features of claim 34, in that, based on a measurement by means of ultrasound, a change in dimension and / or a change in position of at least one component of the plastic molding machine is determined directly or indirectly and a message is output on the basis of the measurement, which is representative of a force and / or an effect of the force on the plastic molding machine and / or on a molding tool.

/ 46

83 163 28

The invention can be used to different forces and / or their

To record effects on the plastic molding machine. Examples of such forces would be an injection force, an ejector force, or one of them

Closing unit of the plastic molding machine applied clamping force.

Of course, these examples can be combined with one another or the invention can be used separately for these examples.

Another advantage of the invention is that a force flow can be measured directly and / or the measuring device can be freely positioned and / or a higher accuracy of the measurement results can be achieved.

Within the scope of the invention, a direct measurement can be understood as a measurement of the dimensional change in the direction of the force. An indirect measurement can be understood as a measurement which allows a conclusion to be drawn about the change in dimension in the direction of the force, for example by inferring a change in dimension from a change in position.

It should be noted that the at least one ultrasound device can be designed as an integral transmitter or receiver. Alternatively, the at least one ultrasound device can be designed in several parts. This means that it has at least one transmitter unit and - separately from it - at least one receiver unit. However, it can preferably be provided that the at least one transmission unit and the at least one reception unit are formed by the same components for executing a transmission function and a reception function.

For example, when using a piezo element (e.g. piezo speaker), it can be provided that the piezo element is excited to oscillate, which leads to an ultrasound emission. Such a piezo element can also be used as a receiving unit by reversing the piezo effect.

Counterforces can be, for example, buoyancy forces generated by internal mold pressure in a mold or Newtonian reaction forces.

/ 46

83 163 28

An advantage of using ultrasound to measure a change in dimension and / or a change in position of the at least one component is that the use of ultrasound enables far more precise resolutions of the measurement in comparison to measurement methods (for example a measurement using a strain gauge) which are in the state are known in the art. A higher resolution of the measurement means a growing measurement accuracy. Furthermore, there is the advantage that the higher resolution also allows, for example, movement or deformation of the at least one component, a clamping unit, an injection unit or even the entire plastic molding machine, preferably over a period of time, the deformation not only drawing conclusions about one Clamping force allows, but also on other forces acting in the process (such as an injection force resulting from the injection pressure).

Any part of the plastic molding machine that is exposed to a force or counterforce by at least one drive of the plastic molding machine can be used as at least one component.

The force can be a closing force, for example.

By arranging at least one transmitter unit on the at least one component and / or integrating it into the at least one component and / or by connecting the at least one transmitter unit to the at least one component via a sound-conducting connection and connecting a receiver unit to the at least one component and / or is integrated in the at least one component and / or in that at least one receiving unit is connected to the at least one component via a sound-conducting connection, can be transmitted in a very precise manner by transmitting and receiving the at least one ultrasonic signal a change in position and / or a change in size of the at least one component is given information.

The sound-conducting connection can be implemented, for example, via a metallic contact or a - preferably temperature-resistant - gel. The gel can improve the coupling of ultrasound signals emitted for the purpose of measurement.

/ 46

83 163 28

For the purpose of measurement can be emitted by the ultrasound device

Ultrasound signals are emitted modulated to facilitate the recognition of the signal during the measurement by detecting the modulation.

Signals, which are measured by the ultrasound device, in particular by the receiving unit, and supplied to the evaluation unit, can be subjected to preprocessing in the sense of a message before being transmitted to the evaluation unit. Such processing can include, for example, an analog-digital conversion of the signals and / or the use of various filters.

A change in position can be understood to mean a change in the position of the at least one component relative to another. Such a relative component can be, for example, a frame of the plastic molding machine or another component of the plastic molding machine.

Examples of messages that are representative of the force itself and / or an effect of the force on the plastic molding machine and / or the molding tool would be, for example, the output of the values of the specific dimensional change or position change or a force change or a (closing) force profile.

Advantageous embodiments of the invention are defined in the dependent claims.

It can be provided that the at least one component is a spindle driven by the at least one drive. For example, a ball screw can also be used. It can preferably be provided that a change in length and / or a change in cross-section of the spindle can be determined by the evaluation unit. Of course, a connection between these two quantities (change in length and change in cross-section of the spindle) can also be established by Hook's law. The elastic deformation of the spindle gives direct information about a prevailing force which acts on the spindle.

/ 46

83 163 28

Provision can preferably be made for the spindle to be connected or connectable to an ejector unit of the plastic molding machine, as a result of which the force acting on the spindle can be measured. The evaluation unit can be designed to output a momentarily acting ejector force as part of the message on the basis of the specific change in dimension and / or the change in position of the spindle.

Furthermore, it can be provided that the at least one component of the injection unit is a component that can be driven by the at least one drive - preferably a plasticizing screw. It can also be provided, for example, that the drivable component of the injection unit is an injection piston (which is used, for example, to inject the plasticized mass into the cavity). It can preferably be provided that a change in length of the drivable component of the injection unit can be determined by the at least one evaluation unit. In the context of such an embodiment, the evaluation unit can be designed to output an instantaneously acting injection force as part of the message based on the specific dimensional change and / or the change in position of the drivable component of the injection unit.

In an exemplary embodiment variant, it can be provided that the at least one component is at least one injection cylinder (often also called mass cylinder in the prior art), wherein an axial change in length can be determined by the at least one ultrasound unit. For example, it can be provided that the evaluation unit can determine a contact pressure of the at least one injection cylinder, and preferably a force profile, due to the axial change in length. Before the injection of a plasticized mass into at least one mold cavity of the at least one molding tool, an injection cylinder is brought up to the molding tool or a component connected to the molding tool and pressed on with a contact pressure. This contact pressure serves to ensure that the injection cylinder does not stand out from the mold or the component connected to the mold during injection.

Alternatively or additionally, it can be provided that the at least one component is at least part of a piston-cylinder unit. The / 46

83 163 28

Evaluation unit be designed to detect a change in length of at least a part of a piston-cylinder unit, preferably by the

Evaluation unit can be determined on a force exerted by the piston-cylinder unit. The piston-cylinder unit can be part of a hydraulic or

Pneumatic system be formed.

The plastic molding machine preferably has the following:

- At least two mold mounting plates, which are suitable for transmitting a closing force to a mold tool mounted thereon

- A closing force mechanism, which is designed to apply the closing force to the at least two platen, wherein the at least one component is a component of the clamping unit, which is exposed to the force by the closing force and / or a counterforce opposing the closing force, the output to be output Message of the evaluation unit represents an effect of the clamping force application on the clamping unit and / or a mold.

It can preferably be provided that the at least one drive is designed as a closing force mechanism of the plastic molding machine.

It can preferably be provided that the at least one ultrasound device is designed to carry out a transit time measurement. This represents a simple way of measuring the plastic molding machine. Of course, in principle it is also conceivable to use interferometric measurements or measurements based on diffraction effects.

Within the scope of the invention, a measurement can be understood to mean that the transmitter unit emits at least once an ultrasound signal, the reflected, diffracted or otherwise changed signal of the receiver unit is detected by the interaction with the at least one component. With pulsed transmission of the signals, which can be advantageous in connection with the transit time measurement, the ultrasound pulses emitted by the transmission unit can be transmitted very often in a short time. As a result, several thousand measurements (and more) can be carried out per second.

/ 46

83 163 28

The continuous emission of ultrasound by the transmitter unit is also conceivable

e.g. B. in connection with interferometric measurements.

It can be provided that the evaluation unit is integrated in the at least one ultrasound device. However, designs are also conceivable in which the evaluation unit is designed by a separate component and the at least one ultrasound device is or can be connected to the evaluation unit.

For example, it can be provided that the function of the evaluation unit is carried out by a central control or regulating unit of the plastic molding machine. However, it is also possible that the at least one ultrasound device can be connected to an evaluation unit via a LAN, WLAN and / or other remote data transmission connections (e.g. Internet).

It can be provided that the evaluation unit is designed to, based on the determined dimensional change and / or the change in position of the at least one component, a momentarily acting closing force and / or a momentarily acting force distribution and / or an existing tool breathing and / or a lifting of the molding tool and / or to determine a contact of the molding tool and preferably to output information about the momentarily acting closing force and / or the momentarily acting force distribution and / or existing tool breathing and / or the lifting of the molding tool and / or the contact of the molding tool as part of the message.

It is preferably provided that the evaluation unit is designed to infer a deformation of the at least one component due to the change in size and / or the change in position of the at least one component, and preferably to output information about the deformation of the at least one component as part of the notification. An example of a deformation is the deformation of a mold platen or part of a toggle mechanism, which are subjected to a bending stress when subjected to a closing force and during injection.

/ 46

83 163 28

It is particularly preferably provided that the evaluation unit is designed to output the message if an injection force and / or an ejection force and / or an ejection force and / or a momentarily acting closing force and / or a present tool breathing and / or a lifting of the tool determined by the evaluation unit Mold and / or a contact of the mold exceeds and / or falls below a predetermined limit. This is a simple way to monitor the plastic molding machine effectively.

For example, it can be provided that the evaluation unit and / or a central control or regulating unit of the plastic molding machine is designed to output the message in the form of an alarm and / or to output the message in the form of a change in a control signal for the plastic molding machine. For example, if a momentarily acting injection force and / or a momentarily acting ejector force and / or a momentarily acting closing force and / or existing mold breathing and / or lifting of the mold and / or contact of the mold exceeds a predetermined limit value, a control signal are output, which causes a process variable to be changed, the change in the process variable entailing a change in the momentarily acting injection force and / or the momentarily acting ejector force and / or the momentarily acting closing force. The variables determined by the evaluation unit can be changed in this way so that they level off again within a predetermined limit range. In other words, a quantity determined by the evaluation unit can be controlled or regulated by such a procedure.

It can be provided that the at least one evaluation unit is designed to output a message to an operator (for example visually or acoustically) or also to a central control or regulating unit of the shaping machine connected to the evaluation unit. Provision can furthermore be made for the at least one evaluation unit to be connected to a central control or regulating unit of the shaping machine, it being possible for the tasks of the at least one evaluation unit to be taken over in part by the central control or regulating unit of the shaping machine.

/ 46

83 163 28

It can additionally or alternatively be provided that the evaluation unit is designed to output a message if a momentarily acting force distribution determined by the evaluation unit deviates from a predefinable reference force distribution. Accordingly, it can be provided that if an instantaneously acting force distribution deviates from a predefinable reference force distribution, the force distribution is corrected by the evaluation unit. Particularly in the case of plastic molding machines with a plurality of pull or push rods, in which the closing force is introduced via pressure pads via the pull or push rods, it can then be provided that each pressure pad can be controlled separately in order to control a force distribution.

The fact that the force distribution deviates from the reference force distribution can be understood, for example, to mean that the force distribution leaves tolerance ranges or a tolerance band around the reference force distribution.

It can preferably also be provided that the evaluation unit is connected or can be connected to a display device for displaying the message. For example, it can be provided that the detected quantities are displayed on a screen for the operator or only if a determined quantity exceeds a predetermined limit value, a warning signal is output, which is designed, for example, as an alarm lamp.

It can preferably be provided that the at least one transmitting unit and the at least one receiving unit are structurally combined in one unit, and preferably the at least one transmitting unit and the at least one receiving unit are formed by the same components for fulfilling a transmitting function and a receiving function.

It can be provided that the at least one component is at least one of the at least two mold mounting plates. In one exemplary embodiment, it can be provided that a change in thickness (change in dimension) of at least one of the at least two mold clamping plates is measured by the ultrasound device, the mold clamping plates being subjected to a closing force / 46

83 163 28 deform elastically. In particular, the thickness of at least one of the at least two mold mounting plates can be reduced under the action of the closing force (also called compression).

However, it can also be provided that the at least one component is at least one pull or push rod which penetrates the at least two mold mounting plates. For example, in shaping machines with pull or push rods, it can be provided that a change in length of the pull or push rod is measured by means of an ultrasound device and that the evaluation unit is designed, based on the change in length of the pull or push rod, a pull or push force which is transmitted by means of the pull or push rod, and thus to determine a closing force which is exerted on a mold via the mold mounting plates. This procedure represents a particularly simple way of determining a distribution of the closing force.

It can be provided that the at least one component is a machine frame connected to the plastic molding machine. In particular, it can also be provided that a closing force can be determined by the evaluation unit via a change in dimension (or a deformation) of the machine frame.

For example, it can also be provided that at least one mold is arranged between the at least two mold mounting plates, the at least one component being at least part of the at least one mold.

The at least one component can preferably also be formed as part of the closing force mechanism, the closing force mechanism preferably having a toggle lever mechanism. For example, in an exemplary embodiment variant, it can be provided that the at least one component is a lever of the toggle lever mechanism and that a change in dimension of the toggle lever mechanism, more precisely the lever, is determined by applying the closing force by means of the ultrasound device and the evaluation unit.

/ 46

83 163 28

At least two ultrasound devices can be provided, with at least two transmitter units and at least two receiver units being arranged on the at least one component of the clamping unit, which is subjected to a force by the closing force application and / or a counterforce opposing the closing force, and / or with a sound-conducting connection with the at least one component is connected and / or integrated in the at least one component. As an alternative or in addition, at least two ultrasound devices can be provided, at least two transmitter units and at least two receiver units being arranged on at least two components of the clamping unit, which are subjected to a force due to the clamping force application and / or a counterforce opposing the clamping force, and / or with a sound-conducting connection connected to the at least two components and / or integrated into the at least two components. An interaction between the at least two ultrasound devices is also conceivable, so that ultrasound signals emitted by one ultrasound device are received by the other ultrasound device. Force profiles can be recorded particularly easily by using two or more ultrasound devices. The use of several transmitting and / or receiving units can of course also be provided with forces other than the closing force.

It can particularly preferably be provided that the evaluation unit is designed to use separate measurements of the at least one ultrasound device

- a dimensional change of the at least one component and / or

a change in position of the at least one component and / or

- To determine a change in the force acting on the component and / or the opposing force.

It can be provided that a movement of the at least one component is thus determined.

It can be provided that two separate measurements

- are carried out by the same ultrasound device at different times and / or / 46

83 163 28

- Be carried out by at least two ultrasound devices.

Spatially separate measurements can be carried out both by moving the ultrasound unit and by pivoting the ultrasound unit.

In a preferred exemplary embodiment, a closing force and / or a counterforce opposing the closing force can be determined over a longer period of time or in a time interval, for example, by the evaluation unit. For example, not only the closing force that is caused by the closing mechanism can be determined, but also during the process a force that counteracts the closing force and that is created by injecting a molding compound into the mold can be measured and preferably output. Of course, forces other than the closing force can also be determined over a longer period or a time interval.

It can preferably be provided that the evaluation unit is designed to take into account a temperature, preferably determined by a temperature sensor, in the direct or indirect determination of a change in dimension and / or change in position of the at least one component. It can thus be provided that the evaluation unit takes into account a temperature expansion of the at least one component during one, during one or between two measurements. In particular, embodiments with a plasticizing screw or a plasticizing cylinder that are exposed to high temperatures and temperature fluctuations can be an advantage.

It is preferably provided that the evaluation unit is designed to determine the change in size and / or the change in position of the at least one component during the operation of the plastic molding machine.

Further advantages and details of the invention result from the figures and the associated description of the figures.

/ 46

83 163 28

Fig. 1 shows a first embodiment of an inventive

Plastic molding machine in the area of the clamping unit,

Fig. 2 shows another embodiment of an inventive

Plastic molding machine in the area of the clamping unit,

3 shows a third exemplary embodiment of a plastic molding machine according to the invention in the region of the clamping unit,

4 shows a fourth exemplary embodiment of a plastic molding machine according to the invention in the region of the clamping unit,

5 shows a fifth exemplary embodiment of a plastic molding machine according to the invention in the region of the clamping unit,

6 shows a sixth embodiment of a plastic molding machine according to the invention in the area of the clamping unit,

7a, 7b the basic procedure of an evaluation unit by means of two diagrams,

8 shows a seventh exemplary embodiment of a plastic molding machine according to the invention in the region of the clamping unit and

9 shows an eighth exemplary embodiment of a plastic molding machine according to the invention in the region of the clamping unit.

1 shows a first exemplary embodiment of a plastic molding machine - in this exemplary embodiment an injection molding machine - in the region of the clamping unit 1. A movable mold mounting plate 4 can be moved relative to a fixed mold mounting plate 3 by means of a toggle lever mechanism 2, the toggle lever mechanism 2 being driven by a drive spindle 6.

The movable platen 4 is connected to the fixed platen 3 via the tie rods 5. Between the movable platen 4 and the fixed platen 3, a mold 13 can be attached for a molding process.

In order to apply a closing force between the movable platen 4 and the stationary platen 3 with a closing force, the crosshead 9 is moved in the direction of the platen / 46 by means of the drive spindle 6

83 163 28

3, 4 moves, whereby the toggle mechanism 2 stretches and the movable

Platen 4 is moved in the direction of fixed platen 3.

When clamping force is applied to the molding tool 13, the pull or push rods 5 - in this embodiment pull rods - are subjected to a tensile stress, as a result of which the pull or push rods 5 expand in length.

In the exemplary embodiment in FIG. 1, an ultrasound device 10 is arranged on the movable platen 4. In this exemplary embodiment, the receiving unit 10.1 and the transmitting unit 10.2 of the ultrasound device 10 are integrated into one unit (ultrasound device 10) and are connected to an evaluation unit 7 by means of a signal-conducting connection 8, the evaluation unit 7 also being connected to a control or regulating unit of the plastic molding machine (for example central machine control) can be connected or can be integrated in the control or regulating unit of the molding machine.

During a measurement of the ultrasonic device 10, an ultrasonic signal 12 is now emitted by the transmitting unit 10.2, a part of the ultrasonic signal 12 being reflected by the side of the movable platen 4 facing the fixed platen 3 and can be received again by the receiving unit 10.1.

The evaluation unit 7 can be designed to calculate the geometric dimension of the movable platen 4 by means of the measured time between the transmission of the ultrasound signal 12 and the reception of the ultrasound signal 12.

If the movable platen 4 is now subjected to a closing force which is transmitted through the movable platen 4 from the toggle mechanism 2 to the mold 13, which is located between the movable platen 4 and the fixed platen 3, there will be an elastic deformation of the movable platen 4 due to the prevailing compressive stresses, the thickness of the movable platen 4 will decrease.

/ 46

83 163 28

If a measurement is now carried out by the ultrasound device 10 during the application of the closing force, a changed dimension of the movable platen 4 can be determined. The dimension can now be compared by the evaluation unit 7 with a stored dimension of the movable platen 4 and / or with a dimension which has been determined by a reference measurement without applying clamping force. By changing the dimension, a prevailing closing force can now be inferred, for example by Hooke's law due to the deformation, with reference to the known geometric shape and the known material of the movable platen 4, to the existing force (the closing force) is closed.

On the basis of this currently determined closing force, the evaluation unit 7 or the machine control can now be designed to adapt the closing force to a desired closing force, more precisely, to increase or decrease the closing force. This can be done by the evaluation unit 7 by changing the target value, for example by controlling the drive spindle 6 or by changing the mold height via the adjusting nut 17.

FIG. 2 shows a further exemplary embodiment, the ultrasound device 10 being arranged on one of the pull or push rods 5 (pull rod in this example). Here again the transmitter 10.2 and the receiver 10.1 are integrated in one unit. The ultrasound device 10 is connected to the evaluation unit 7 via a signal-conducting connection. The remaining components of the clamping unit 1 are analogous to those in FIG. 1. The exemplary embodiment in FIG. 2 now makes it possible to use the ultrasound device 10 to measure a length of the pull or push rod 5 which will expand due to the tensile forces when the clamping force is applied. An expansion can be measured by the ultrasound device 10, and a closing force can be inferred from the evaluation unit 7 due to the expansion.

The ultrasound device 10 according to the invention is only shown on one of the pull or push rods 5. Corresponding measurements can of course be made at / 46

83 163 28 several - in particular all - pull or push rods 5 are carried out, in particular to measure a distribution of the closing force.

3 shows the same design of a locking unit 1 as shown in the previous figures. However, in FIG. 3 the ultrasound device 10 is arranged on a molding tool 13, which is designed in two parts and has a first molding tool half 14 and a second molding tool half 15. Again, a change in dimension of at least one mold half 14, 15 can be measured by the ultrasound device 10 under the application of closing force and a closing force can be determined by the evaluation unit 7 based on the change in dimension. Furthermore, it is now possible to determine a so-called gaping of the molding tool 13 by the ultrasound device 10, more precisely by the integrated receiving unit 10.1 and the integrated transmitting unit 10.2.

When the mold 13 is opened, an air gap is formed between the first mold half 14 and the second mold half 15. The propagation of an ultrasound signal 10 in air is, however, only limited. As a result, the ultrasound signal 10 loses intensity when the first mold half 14 lifts off from the second mold half 15. A part of the ultrasound signal 10 is also reflected by the second mold half 15, however, due to the damping of the air at the receiving unit 10.1, this is generally no longer measurable.

Such a gaping of the mold 13 can therefore be determined by the ultrasound device 10 when the reflected ultrasound signal 12, which is reflected by the side of the second mold half 15 facing the first mold half 14, can no longer be received. As mentioned, it can be concluded from this that there is a distance between the two mold halves 14, 15. Depending on the time of the process, such a distance can be provided (e.g. as an embossing stroke) or it can be recognized from this that the closing force has been selected too low and the mold 13 begins to gap and the closing force must be increased. As an alternative to automatically increasing the closing force, a warning signal can also be issued.

/ 46

83 163 28

4 shows the locking unit 1 already described in FIG. 1. However, in FIG. 4, several, more precisely five, ultrasonic devices 10 are provided on the movable platen 4. A reception unit 10.1 and a transmission unit 10.2 are in turn integrated in the ultrasound devices 10 and are connected to an evaluation unit 7 via a signal-conducting connection 8. The provision of a plurality of ultrasonic devices 10 results in the advantage that a change in the dimensions of the movable platen 4 can be determined at several positions of the movable platen 4, as a result of which an uneven distribution of closing force along the movable platen 4 can be demonstrated and due to the deformation of the movable platen 4 the closing force can be adjusted if necessary. An inclined position of the movable platen 4 relative to the fixed platen 3 can also be measured by the provision of several ultrasound devices 10.

5 shows an exemplary embodiment in which an ultrasonic device 10 is arranged on each pull or push rod 5 of the clamping unit 1, the ultrasonic devices 10 again each having a receiving unit 10.1 and a transmitting unit 10.2, which are connected to a via a signal-conducting connection 8 Evaluation unit 7 are connected. Similar to FIG. 4, the embodiment of FIG. 5, through the provision of a plurality of ultrasound devices 10, can also determine an uneven deformation of the clamping unit 1, which provides information about an unevenly distributed closing force.

In the exemplary embodiment in FIG. 6, two ultrasound devices 10 are each arranged on a lever of the toggle lever 2, which is part of the toggle lever mechanism 2. Here, too, a length (a geometrical dimension) of the levers of the toggle lever mechanism 2 can be determined and a change in dimension under the application of closing force, which in turn can be inferred by the evaluation unit 7 based on the change in dimension of a present closing force or an uneven distribution of closing force (due to the two ultrasound devices provided 10) can be determined.

7a and 7b show the basic procedure of an evaluation unit 7 by means of two diagrams. The ordinate of the diagrams is the intensity X of the received / 46

83 163 28

Understand signals by the receiving unit 10.1 and the abscissa as time t. For

Explanation of the diagrams of FIGS. 7a and 7b is made to FIG. 1, in which the

Ultrasonic device 10 is arranged on a movable platen 4.

An ultrasound signal 12.1 is emitted by the transmitting unit 10.2 at one time and can be received again as a reflected ultrasound signal 12.2 by the receiving unit 10.1 after a certain period of time. The distance that the ultrasound signal 12.2 has traveled can be calculated from the elapsed time between the transmission of the ultrasound signal 12.1 and the reception of the ultrasound signal 12.2 with the aid of the speed of sound of the ultrasound signal 12 in a material from which the movable platen 4 is made . If this distance is now halved (since the ultrasound signal has traveled back and forth), the thickness of the movable platen 4 can now be determined.

This process, which is shown in FIG. 7a, is to be understood in the case of a movable platen 4 which has not been subjected to a closing force and can therefore serve as a reference measurement which provides information about the thickness of a movable platen 4 without the application of force.

This process is now repeated under the application of closing force to the movable platen 4 (this is shown by FIG. 7b). It can be seen here that an emitted ultrasound signal 12.1 returns to the receiving unit 10.1 significantly earlier than the reflected ultrasound signal 12.3. If the reference value of the ultrasound signal 12.2 is now used, a time difference At between the ultrasound signal 12.3 and the ultrasound signal 12.2 can be recognized, which in turn can be inferred from the dimensional change of the movable platen 4 using the ultrasonic signal speed in the material from which the movable platen 4 is made can.

With the aid of this dimensional change of the movable platen 4, the evaluation unit 7 or the machine control can be designed to infer a closing force based on known material-specific values and dimensions, which is exerted on the movable platen 4.

/ 46

83 163 28

8 shows an exemplary embodiment in which the ultrasound unit 10 is arranged on a drive spindle 6 of the toggle lever mechanism 2. The drive spindle 6 transmits a force from the spindle nut 16 (in this exemplary embodiment designed as a ball screw nut) to the toggle mechanism 2, which transmits the force transmitted by the drive spindle 6 to the movable platen 4 as a closing force. In this case, a geometrical dimension of the drive spindle 6 can be determined and a change in dimension of this length can be measured, wherein the evaluation unit 7 can again infer a current force due to the change in dimension. How the basic procedure of the ultrasound unit takes place is shown, for example, by FIGS. 7a and 7b. Again, the ultrasound device 10 shown in FIG. 8 has an integrated receiving unit 10.1 and transmitting unit 10.2. The ultrasonic unit is in turn connected to the evaluation unit 7 by a signal-conducting connection 8.

In the part of the drive spindle 6, which is located within the spindle nut 16, a non-linear deformation is to be expected, since higher forces are introduced at certain points of the spindle nut 16. Such deformation patterns are known and can be taken into account when determining the dimensional change. Since there is a defined relationship between the force transmitted by the drive spindle 6 and the closing force introduced by the toggle lever mechanism 2 into the movable platen 4, the evaluation unit 7 can be designed to change the length of the drive spindle 6, which is representative of a transmitted force of the drive spindle 6 is to conclude a closing force.

However, it is also possible to detect such a force, which is transmitted to the toggle lever mechanism by the drive spindle 6, by arranging an ultrasound unit 10 on the spindle nut 16, as is illustrated by FIG. 9.

/ 46

83 163 28

Reference symbol list:

Clamping unit

Toggle mechanism fixed mold platen movable mold platen

Drawbar or push rod

Drive spindle

Evaluation unit signal-conducting connection

Cross head

Ultrasound device

10.1 Receiver unit

10.2 Sending unit

Ultrasound signal

12.1 Ultrasound signal

12.2 Ultrasonic signal

12.3 Ultrasonic signal

Mold first mold half, second mold half

Spindle nut

Adjusting nut

X intensity of the received signal t time

At time difference

Claims (34)

Patent claims 1. Plastic molding machine with at least one component which is exposed to a force and / or a counterforce opposing the force by at least one drive, characterized in that at least one ultrasound device (10) with at least one transmitter unit (10.2) for transmitting and at least one receiver unit ( 10.1) for receiving ultrasound, which ultrasound device (10) is or can be connected to an evaluation unit (7), wherein - The at least one transmission unit (10.2) is arranged on the at least one component and / or is connected to the at least one component via a sound-conducting connection and / or is integrated in the at least one component and - The at least one receiving unit (10.1) is arranged on the at least one component and / or is connected to the at least one component via a sound-conducting connection and / or is integrated in the at least one component and - The evaluation unit (7) is designed to determine a change in dimension and / or a change in position of the at least one component directly or indirectly on the basis of a measurement of the at least one ultrasound device (10) and to output a message based on the measurement, which is for the force itself and / or an effect of the force on the plastic molding machine and / or a molding tool (13) is representative. 2. Plastic molding machine according to claim 1, characterized in that the at least one component is a spindle which can be driven by the at least one drive. 3. Plastic molding machine according to claim 2, characterized in that a change in length of the spindle can be determined by the at least one evaluation unit (7). 24/46 83163 28 / eh 4. Plastic molding machine according to one of claims 2 or 3, characterized in that a cross-sectional change of the spindle can be determined by the at least one evaluation unit (7). 5. Plastic molding machine according to one of claims 2 to 4, characterized in that the spindle is connected or can be connected to an ejector unit of the plastic molding machine. 6. Plastic molding machine according to one of claims 2 to 5, characterized in that the evaluation unit (7) is designed to output a momentarily acting ejector force as part of the message due to the specific dimensional change and / or the change in position of the spindle. 7. Plastic molding machine according to one of the preceding claims, characterized in that the at least one component is a component which can be driven by the at least one drive - preferably a plasticizing screw - of the injection unit. 8. Plastic molding machine according to claim 7, characterized in that a change in length of the drivable component of the injection unit can be determined by the at least one evaluation unit (7). 9. Plastic molding machine according to one of claims 7 or 8, characterized in that the evaluation unit (7) is designed to output a momentarily acting injection force as part of the message due to the specific dimensional change and / or the change in position of the drivable component of the injection unit. 10. Plastic molding machine according to one of the preceding claims, characterized by: - At least two mold mounting plates (3, 4) which are suitable for transmitting a closing force to a mold (13) mounted thereon - A closing force mechanism, which is designed to apply the closing force to the at least two mold mounting plates (3, 4), the at least one component being a component of the closing unit (1), which is the force of the closing force and / or one of the 25/46 83163 28 / eh Closing force is exposed to opposing counterforce, the message to be output by the evaluation unit (7) being an effect of Clamping force applied to the clamping unit (1) and / or a mold (13) represents. 11. Plastic molding machine according to claim 10, characterized in that the at least one drive is designed as a closing force mechanism of the plastic molding machine. 12. Plastic molding machine according to claim 10 or 11, characterized in that the evaluation unit (7) is designed to, due to the specific dimensional change and / or the change in position of the at least one component of the clamping unit (1), a momentarily acting clamping force and / or a momentarily acting force Force distribution and / or existing tool breathing and / or lifting of the molding tool (13) and / or contact of the molding tool (13) and preferably information about the momentarily acting closing force and / or the currently acting force distribution and / or the present tool breathing and / or to issue a lifting of the molding tool and / or a contact of the molding tool in the context of the message. 13. Plastic molding machine according to one of claims 10 to 12, characterized in that the evaluation unit (7) is designed to output the message if a currently acting closing force determined by the evaluation unit (7) and / or an existing tool breathing and / or a Lifting off the molding tool (13) and / or contact of the molding tool (13) exceeds and / or falls below a predefinable limit value. 14. Plastic molding machine according to one of claims 10 to 13, characterized in that the at least one component is at least one of the at least two mold mounting plates (3, 4). 15. Plastic molding machine according to one of claims 10 to 14, characterized in that the at least one component is at least one pulling or pushing rod passing through the at least two mold mounting plates (3, 4) (5). 26/46 83163 28 / eh 16. Plastic molding machine according to one of claims 10 to 15, characterized in that the molding tool (13) is arranged between the at least two mold mounting plates (3, 4), the at least one component being at least part of the molding tool (13). 17. Plastic molding machine according to one of claims 10 to 16, characterized in that the at least one component is part of the closing force mechanism, the closing force mechanism preferably having a toggle lever mechanism (2). 18. Plastic molding machine according to one of the preceding claims, characterized in that the ultrasonic device (10) is designed to carry out a transit time measurement. 19. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is integrated in the at least one ultrasound device (10). 20. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed, on the basis of the specific dimensional change and / or the change in position of the at least one component, to have a momentarily acting force distribution and / or a lifting of the at least one component and / or to determine a contact of the at least one component and preferably to output information about the currently acting force distribution and / or a lifting of the at least one component and / or a contact of the at least one component as part of the message. 21. Plastic molding machine according to claim 20, characterized in that the evaluation unit (7) is designed to output the message if a force distribution currently acting determined by the evaluation unit (7) deviates from a predefinable reference force distribution. 22. Plastic molding machine according to claim 20, characterized in that the evaluation unit (7) is designed to output the message, if one 27/46 83163 28 / eh momentarily determined force and / or a by the evaluation unit (7) Lifting off the at least one component and / or a contact of the at least one component exceeds and / or falls below a predefinable limit value. 23. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to infer a deformation of the at least one component based on the change in size and / or the change in position of the at least one component, and preferably information about the deformation of the to output at least one component as part of the notification. 24. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) and / or a central control or regulating unit of the plastic molding machine is designed to output the message in the form of an alarm and / or the message in the form of a change Output control signal for the plastic molding machine. 25. Plastic molding machine according to claim 24, characterized in that the control signal to be changed is a target variable, preferably a target closing force. 26. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is connected or can be connected to a display device for displaying the message. 27. Plastic molding machine according to one of the preceding claims, characterized in that the at least one transmitter unit (10.2) and the at least one receiver unit (10.1) are structurally combined in one unit, preferably the at least one transmitter unit (10.2) and the at least one receiver unit (10.1 ) are formed by the same components for fulfilling a send function and a receive function. 28/46 83163 28 / eh 28. Plastic molding machine according to one of the preceding claims, characterized in that the at least one component is a machine frame connected to the plastic molding machine. 29. Plastic molding machine according to one of the preceding claims, characterized in that at least two ultrasonic devices (10) are provided, with at least two transmitter units (10.2) and at least two receiver units (10.1) on the at least one component of the plastic molding machine, which at least one component by the at least one drive is subjected to a force and / or a counterforce opposing the force, arranged and / or connected to the at least one component with a sound-conducting connection and / or integrated into the at least one component. 30. Plastic molding machine according to one of the preceding claims, characterized in that at least two ultrasonic devices (10) are provided, with at least two transmitter units (10.2) and at least two receiver units (10.1) on at least two components of the plastic molding machine, which at least two components by the at least a drive is subjected to a force and / or a counterforce opposing the force, arranged and / or connected to the at least two components with a sound-conducting connection and / or integrated into the at least two components. 31. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to use separate measurements of the at least one ultrasound device (10). - a dimensional change of the at least one component and / or a change in position of the at least one component and / or - To determine a change in the force acting on the component and / or the opposing force. 32. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to 29/46 83163 28 / eh preferably determined by a temperature sensor - temperature in the direct or indirect determination of a change in size and / or Change in position of the at least one component must be taken into account. 33. Plastic molding machine according to one of the preceding claims, characterized in that the evaluation unit (7) is designed to determine the change in size and / or the change in position of the at least one component during operation of the plastic molding machine. 34. Method for checking at least one component of a plastic molding machine, characterized in that a change in dimension and / or a change in position of at least one component of the plastic molding machine is determined directly or indirectly on the basis of a measurement by means of ultrasound and a message is output on the basis of the measurement, which for a force and / or an effect of the force on the plastic molding machine and / or on a molding tool (13) is representative.